Now I know I'm not going to be popular with this response, but in the UK there have been two incidents of this type in the last 25 years. Michael Ryan in Hungerford and Thomas Hamilton in Dunblain. The UK government banned handguns and made it very difficult to obtain any other type of firearm legally. Since then there have been no other incidents of this type. I think that in the US you have to accept that if you make firearms available to the general public, eventually, this type of scenario will occur.